What is a PLN
A PLN (Professional Learning Network) is the entire collection of people with whom you engage and exchange information, usually online. It may consist of any social media web resource that allows you to share with others, whether it is thoughts, pictures, or words. The PLN may consist of bloggers, tweeters, or any online resource that will allow you to grow as an educator.
16 Resources about Personal Learning Networks

Professional Learning Network
If you are going to get into the blog world, get a Google Accountand set up Google Reader. When you are in your Google Account, you will find Google Reader in the drop-down menu under "More". It is a "no brainer" to use and will keep your blogs organized and ready to read when you are. Bloglines will do the same thing but if you have a Google Account you are set up to use a plethora of collaborative tools!

Note from Marge Runkle:
If you are considering the development of a personal professional learning network using the blogosphere and you are uncertain where to begin, I would suggest that you visit Blogs on Educational Blogging. This site has a plethora of educational blogs to get you started. Some are very prolific and some are sparse and there are a wide variety of foci in the list but it is a beginning. It may take a few reads before you discover a voice that resonates on your soundboard. When you have found someone who fits your needs, save the blog to your Google Reader. It will save the updates as they appear and you can scan the topics and choose which to read when you are able and let the rest go. Here is a site that contains some blogs for nearly everyone! The “Most Popular” Blogs That Might Also Be Useful To Educators

What DUTY do we owe to the PLN? What is our RESPONSIBILITY as a member of the PLN?
My duty to the PLN is to contribute, to ask, to answer, to share, to participate, and to collaborate. My responsibility as a PLN member is to listen to all voices, to promote interaction and engagement, and to grow professionally. @dpeter via Twitter

5 Ways to Build Your 1.0 and 2.0 Personal Learning Network

Blogs According to Core Subject Area
Education Blogs by Discipline

Language Arts
The English Teacher Blog
NCTE Inbox
The Teacher's View
The English Blog

Mathematics
Misterteacher.com

Twitter

Twitter is another low maintenance resource that can be a form of personal professional learning network. All you need is an account and it is free! You don't have to fully participate. Participation comes with comfort. Lurk for awhile until you get the hang of it. Lurking is "OK".
Here are some Tweeters that you could follow for starters and who sometimes ask thought provoking questions or will point you in an interesting direction: Will Richardson (willrich45), Alan November (globalearner), Thomas Whitby (tomwhitby), David Peter (dpeter), Ken Washburn (kdwashburn), Bernie Dodge (berniedodge), David Warlick (dwarlick), Chris Anderson (TEDchris). Occasionally these individuals share some personal moments, but I have discovered that those moments have made me more comfortable with them and their views and thoughts. You can then begin to add people from the York Tech Cloud: Dr. Tiffany Wright (twrightycst), Marge Runkle (mrunkle), Carol Zortman (clz917). There are others at Tech who have accounts and are beginning to use them! Here are some tweeters from the ASCD: ASCD authors and experts: @grantwiggins, @robertjmarzano, @nancyfrey, @judywillis, @joe_dimartino, @robyn_mindsteps, @artcosta